The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingInstallation
Install accelerator pedal rod
Install the accelerator pedal rod with the 2 bolts.
Torque: 5.4 N*m (55 kgf*cm, 48 in.*Lbf)
Connect the accelerator pedal position sensor
connector.
Connect cable to negative battery terminal
...
Manual air conditioning system
Air conditioning controls
Fan speed control switch
Temperature control switch
On/off switch
Windshield defogger switch
Rear window and outside rear view mirror defoggers* switch
Airflow mode control switch
Outside/recirculated air mode switch
"A/C" switch
"MAX A/C" switch
*: If equipped
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Check for intermittent problems
Hint:
Inspect the vehicle's ecm using check mode. Intermittent
problems are easier to detect with the intelligent tester when
the ecm is in check mode. In check mode, the ecm uses 1
trip detection logic, which is more sensitive to malfunctions
than normal mode (default), which uses 2 trip detec ...